Can't see a glass object through another glass object in Eevee
Unfortunately this is a limitation of the render engine.

https://blenderartists.org/t/glass-material-cycles-vs-eevee-object-with-thickness/1113232

"You can’t. Cycles properly emulates refraction because it is a ray tracing engine, where light rays are simulated and change direction as they enter and get out of the glass, in a realistic way. For every pixel, it finds what parts of the scene affect it.

Eevee is a rasterization engine: for every vertex (part of the scene), it finds what pixels it corresponds to. It is much faster, but doesn’tactually emulate light. It uses tricks to have shadows, etc. In this case, refraction uses the normal of the point in the surface to deform what part is seen behind it, using information from the screen, but there is no light being deformed. The same happens for reflections.

The only way would be to add ray tracing to some parts of eevee, as real time raytracing is developed (which the recent announcements from microsoft and ATI were about).

PD: this happens with every single real time engine: UE4, Unity… refractions are one of the areas that really need ray tracing."